Former Prime Minister Yasuhiro Nakasone, a legendary figure in Japanese politics who turned 100 on Sunday, has expressed hope that "serious efforts" will be made to amend the postwar Constitution.

Nakasone, a conservative who served as prime minister from November 1982 to November 1987, is the second one-time prime minister to live to 100. The first was Naruhiko Higashikuninomiya, who died in 1990 at the age of 102.

With Japan set to enter a new era next year after Emperor Akihito abdicates, Nakasone said he feels "deep emotion" for having lived in four eras — Taisho, Showa, Heisei and the one to begin next May with the ascension of Crown Prince Naruhito to the Chrysanthemum Throne.